This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The ability to tag proteins with GFP and its color variants has revolutionized cell biology. In particular the CFP/YFP pair and the GFP/Cherry pair of fluorescent proteins make excellent FRET partners to measure the proximity of two proteins in vivo. We plan to develop a new method to tag proteins with the GFP variants.